Speed sensor

ABSTRACT

In an embodiment, a speed sensor includes a first portion, a second portion, and a third portion. The first portion includes a sensing assembly for generating a signal associated with a movement of an object external to the speed sensor. The second portion includes a wiring harness for transferring the generated signal to a device external to the speed sensor. The first portion and the second portion are joined. The third portion is over-molded over a point of the speed sensor where the first portion joins the second portion. Over-molding the third portion at the point may act to seal the point from outside contaminants. Moreover, over-molding the third portion at the point may act to strengthen the speed sensor at the point.

RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalPatent Application No. 61/941,660, filed on Feb. 19, 2014 and titled“Turbo Speed Sensor”, the contents of which are incorporated byreference as though fully set forth herein.

BACKGROUND

An internal combustion engine (ICE) may include various devices that mayimprove an efficiency of operation of the ICE. For example, an ICE mayinclude a turbocharger device. The turbocharger device may improve anefficiency of the ICE by forcing air into a combustion chamberassociated with the ICE.

Turbocharger devices may employ various components that may force airinto a combustion chamber of an ICE. For example, a turbocharger devicemay include a turbine wheel, a compressor wheel, and a shaft. The shaftmay connect the turbine wheel with the compressor wheel such that whenthe turbine wheel rotates the compressor wheel rotates.

Exhaust gases produced by the ICE may be routed to the turbochargerdevice where they may be used to rotate the turbine wheel. As theturbine wheel rotates it causes the compressor wheel to rotate. Rotationof the compressor wheel may cause ambient air to be pulled in andcompressed by the turbocharger device. The compressed air may be pumpedinto the ICE's combustion chamber.

A speed sensor may be used to sense a speed of a turbocharger. Forexample, a turbo speed sensor may be used to sense a speed at which aturbine wheel and/or compressor wheel rotates in a turbocharger. Thesensed speed may be used to measure a performance of the turbocharger.

A speed sensor may be manufactured using various over-molding processes.The over-molding processes may involve using various utilizing pressuresand temperatures to accommodate the over-molding. The pressures and/ortemperatures used for over-molding often are selected in order toobviate damage that may occur to the speed sensor during the manufactureof the speed sensor. Using too high of a temperature and/or pressure maycause damage to the speed sensor. However, using too low of atemperature and/or pressure may not provide a good seal for the speedsensor.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate one or more embodiments describedherein and, together with the description, explain these embodiments.The components of the drawings are not necessarily drawn to scale, theemphasis instead being placed upon illustrating principles of thepresent disclosure. In the drawings:

FIG. 1 illustrates an example embodiment of a speed sensor;

FIG. 2 illustrates a first view of an example embodiment of a firstportion of the speed sensor;

FIG. 3 illustrates an example embodiment of a sensing assembly that maybe contained in the first portion;

FIG. 4 illustrates a second view of the first portion;

FIG. 5 illustrates an example embodiment of a second portion of thespeed sensor;

FIG. 6. illustrates a cut-away view of the second portion;

FIG. 7 illustrates a subassembly that includes a joined first portionand second portion;

FIG. 8 illustrates an example embodiment of a third portion of the speedsensor over-molded over the joined first portion and second portion; and

FIG. 9 is a flow chart of example acts that may be performed to producea speed sensor.

DETAILED DESCRIPTION

Features described herein may be used, for example, in the manufactureof a speed sensors such as, turbo speed sensors. In an embodiment, aspeed sensor is divided into three distinct portions. A first portionincludes a sensing assembly that is over-molded with a housing. A secondportion includes a wiring harness. The first portion is joined with thesecond portion to produce a subassembly of the speed sensor. Thesubassembly is over-molded with a third portion. The third portion mayseal the point of the speed sensor where the first portion joins thesecond portion. Moreover, the third portion may act as a flange for thespeed sensor to accommodate mounting the speed sensor at a fixedposition.

FIG. 1 illustrates an example embodiment of a speed sensor 100 that mayimplement one or more features described herein. Referring to FIG. 1,speed sensor 100 may include, for example, a first portion 200, a secondportion 500, and a third portion 800.

The first portion 200 may sense a movement (e.g., rotation) of an objectthat is external to the speed sensor 100. The external object may be,for example, a turbine and/or compressor wheel contained in aturbocharger and the sensed movement may be a rotation of that wheel.The speed sensor may generate a signal based on the sensed movement. Thegenerated signal may be an electrical signal such as, for example, anelectrical pulse. The signal may be transferred from the first portion200 to the second portion 500 via one or more connections that may bemade between the first 200 and second 500 portions.

The second portion 500 may transfer the signal from the first portion200 to a device that is external to the speed sensor 100. The externaldevice may be, for example, a computer that may determine a speedassociated with the external object based on the signal.

The third portion 800 may accommodate mounting the speed sensor 100.Moreover, the first portion 200 and the second portion 500 may beconnected together to form a subassembly. The third portion 800 may beover-molded over the subassembly to provide a seal for the connectionbetween the first portion 200 and the second portion 500.

As will be described further below, the first portion 200 includes ahousing and a sensing assembly. The housing is over-molded over thesensing assembly and acts to protect the sensing assembly duringmanufacture and/or operation of the speed sensor 100. The sensingassembly includes a coil and a lead frame. The coil senses a movement ofthe external object and produces a signal based on the sensed movement.The lead frame, inter alia, transfers the signal to the second portion500 via connections between the first and second portion 500.

The second portion 500 includes a housing and a wiring harness. A firstend of the wiring harness connects to the first portion 200 viaterminals. A second end of the harness connects to an external device.The wiring harness includes electrically conductive wires which carrythe signal from the first portion 200 to an external device. Theexternal device may identify a speed of the object based on the signal.Moreover, the external device may control an operation of another object(e.g., a turbocharger) based on identified speed.

The first portion 200 and the second portion 500 are joined to form asubassembly. The subassembly includes an electrical connection betweenthe first 200 and second 500 portions. The third portion 800 isover-molded over the connection made between the first 200 and second500 portions. Here, the third portion 800 acts as a seal for theconnection.

In addition, the third portion 800 contains provisions for mounting thespeed sensor 100 when, for example, the speed sensor 100 is placed inoperation. Here, the third portion 800 acts as a flange for the speedsensor 100.

It should be noted that breaking the speed sensor 100 into portions,such as portions 200, 500, and 800, may ease manufacturing of the speedsensor 100. For example, having the first portion 200 and the secondportion 500 as separate portions may enable the first portion 200 to bemanufactured without being encumbered by the wiring harness contained inthe second portion 500.

FIG. 2 illustrates a first view of the first portion 200 of the speedsensor 100. Referring to FIG. 2, first portion 200 may include a sensingassembly 300. As will be described further below, sensing assembly 300may include a bobbin, magnet 314, coil, and a lead frame. The sensingassembly 300 may sense a movement (e.g., rotation) of an object such as,for example, a turbine wheel and/or compressor wheel that may rotate ina turbocharger. The sensing assembly 300 may generate a signal (e.g., anelectrical pulse) based on the sensed movement. The generated signal maybe provided by the sensing assembly 300 to the second portion 500 of thespeed sensor 100.

FIG. 3 illustrates an example embodiment of a sensing assembly 300 thatmay be used with speed sensor 100. Referring now to FIGS. 2 and 3,sensing assembly 300 may include a bobbin 310, a coil 312, and a leadframe 340. The coil 312 may include wire (e.g., enameled copper wire)that may be wrapped around one end of the bobbin 310. The coil 312 may,for example, sense a movement of an object and generate a signal basedon the sensed movement. Here, sensing may involve magnetics. Forexample, an electric current may be applied to the coil 312 to generatea magnetic field. The field may be disturbed by movement of the objectsuch as, a turbine wheel. The signal generated by the coil 312 may bebased on the disturbance to the field caused by the movement of theobject.

Bobbin 310 may be molded from an electrically non-conductive material.Bobbin 310 may be staked with one or more electrically conductive pins313. The coil 312 may be terminated at the pins 313. In an embodiment,the coil 312 contains two ends and the bobbin 310 is staked with twopins 313. Here, one end of the coil 312 is wrapped around one of thepins 313 and the other end of the coil 312 is wrapped around the otherpin 313.

Magnet 314 (FIG. 2) may be affixed to bobbin 310. The magnet 314 may beused in conjunction with the coil 312 to generate the magnetic field. Inan embodiment, the magnet 314 is a samarium-cobalt (SmCo) magnet suchas, for example, a Sm₂Co₁₇ magnet. It should be noted, however, that inother embodiments other suitable types of magnets may be used.

A pin 313 may be placed inside an opening 344 in lead frame 340 and makeelectrical contact with the lead frame 340 at the opening 344 of thelead frame 340. Note that the opening 344 may enable inspection of theconnection between the pin 313 and the lead frame 340. Moreover, itshould be noted that one or more welding electrodes may be placed on oneor more sides of opening 344 to weld the pin 313 to the lead frame 340.

Lead frame 340 may include one or more terminals 342. The terminals 342may be electrically conductive. For example, in an embodiment, theterminals 342 are made of a metal that is electrically conductive. Themetal may include, for example, nickel-plated brass. Note that in otherembodiments, other electrically conductive materials may be used. Aswill be described further below, terminals 342 may transfer a signalgenerated by coil 312 to the second portion 500 of speed sensor 100.

Lead frame 340 may include provisions for mounting bobbin 310. Forexample, lead frame 340 may include engagement features (e.g., hooks)which may engage the bobbin 310 and hold the bobbin 310 in place. Here,for example, the lead frame 340 may act as a carrier for bobbin 310.

FIG. 4 illustrates a second view of the first portion 200. Referring toFIG. 4, the first portion 200 may include a housing 410. The housing 410may house the first portion 200. The housing 410 may be made of aliquid-crystal polymer (LCP), although, other materials may be used. Thehousing 410 may include hole 412, groove 414, ribs 422, and ridges 420.The housing 410 may be over-molded over sensing assembly 300 (FIG. 3)during the manufacture of the first portion 200.

Hole 412 may provide an opening through housing 410 to bobbin 310. Ahole (not shown) corresponding to hole 412 may be located on housing 410at a location that is opposite hole 412. In an embodiment, hole 412 andthe corresponding hole are used to hold sensing assembly 300 in placewhile housing 410 is over-molded over sensing assembly 300.

Groove 414 may provide placement for an O-ring that may be used withspeed sensor 100. The O-ring may provide, for example, a seal for thespeed sensor 100 after the speed sensor 100 is placed in operation.Groove 414 may be shaped to accommodate the O-ring. The shape mayinclude, for example, one or more tapered edges.

Ribs 422 accommodate joining (e.g., bonding) the first portion 200 andthird portion 800 together. As will be described further below, in anembodiment, the first portion 200 and the second portion 500 are joinedtogether. After the first portion 200 and the second portion 500 arejoined, the third portion 800 is over-molded over the joined first 200and second 500 portions. Here, the ribs 422 may melt during theover-molding of the third portion 800 over the joined first 200 andsecond 500 portions thereby accommodating joining the first portion 200and the third portion 800 together.

Ridges 420 may protrude from housing 410. Ridges 420 may accommodate analignment of the first portion 200 with the second portion 500 when thefirst 200 and second 500 portions are assembled together. For example,ridges 420 may be keyed to accommodate a specific alignment of the firstportion 200 with the second portion 500 when the first 200 and second500 portions are joined together.

FIG. 5 illustrates an example embodiment of the second portion 500 ofspeed sensor 100. Referring to FIG. 5, second portion 500 may include ahousing 524 and a wiring harness 526. The housing 524 may be used tohouse the second portion 500. The housing 524 may be made of LCP,although, other materials may be used. The housing 524 may includeridges 520 and ribs 522.

The wiring harness 526 may provide a connection between the speed sensor100 and an outside source (e.g., a computer). The connection may carryvarious signals between the speed sensor 100 and the outside source.These signals may include, for example, readings that may be provided bythe speed sensor.

The wiring harness 526 may include a terminal 528 that may be used toelectrically connect to the first portion 200 and enable electricalsignals to be transferred between the first portion 200 and the secondportion 500. Terminals 528 may be made of an electrically conductivematerial (e.g., copper). As will be described further below, wiringharness 526 may include electrically conductive wires which areterminated by terminals 528.

Ridges 520 may protrude from housing 524. Ridges 520 may accommodate analignment of the second portion 500 with the first portion 200 when thefirst 200 and second 500 portions are assembled together. For example,ridges 520 may be keyed to accommodate a specific alignment of thesecond portion 500 with the first portion 200 when the first 200 andsecond 500 portions are joined together.

Ribs 522 accommodate joining the second portion 500 and third portion800 together. As will be described further below, in an embodiment, thefirst portion 200 and the second portion 500 are joined (e.g., welded)together. After the first portion 200 and the second portion 500 arejoined, the third portion 800 is over-molded over the joined first 200and second 500 portions. Here, the ribs 522 may melt to accommodatejoining the second portion 500 and the third portion 800 together.

FIG. 6 illustrates a cutaway view of the second portion 500. Referringto FIG. 6, the second portion 500 may contain a seal 620, a washer 622,and wires 624. The seal 620 may be an environmental seal that act toprevent contaminants from entering the housing 524. The seal 620tapered. Tapering the seal 620 may act to secure placement of the seal620 in housing 524. The washer 622 may be a backing washer that may actto secure the wires 624 in the housing 524 and prevent the wires 624from exiting the housing 524 after the housing 524 is, for example,over-molded onto the wiring harness 526.

The seal 620 and/or the washer 622 may be made of a pliable material. Inan embodiment, seal 620 is made from an elastomer and washer 622 is madefrom a rigid polymer. Note that housing 524 may include one or more lips626 which may further secure placement of the washer 622 and/or the seal620 in housing 524.

Wires 624 may include an electrically conductive material (e.g., copper)that may be used to conduct electrical signals. Wires 624 may includeinsulation to prevent conduction of electrical signals between the wires624. Moreover, wires 624 may be twisted to obviate coupling of straysignals to the wires 624. Wires 624 may be terminated with terminals528.

Seal 620 and washer 622 may act to accommodate a positioning the wires624 in the second portion 500. Specifically, seal 620 and washer 622 mayinclude holes that may accommodate an alignment of the wires 624. Here,for example, the alignment may include a predefined spacing between thewires 624. Moreover, alignment may include an angular position of thewires 624 with respect to a longitudinal aspect of the second portion500.

For example, the seal 620 and washer 622 may include holes that mayenable the wires 624 to be aligned with respect to axis 628. Here, forexample, axis 628 may be a longitudinal center axis for the secondportion 500. The holes may provide for an alignment of wires 624 suchthat the wires 624 are equidistant from the axis 628 and parallel to theaxis 628 within a predefined tolerance.

FIG. 7 illustrates an example embodiment of a subassembly 700 thatincludes the first portion 200 and the second portion 500. Referring toFIG. 7, as noted above, ridges 420 and 520 may be keyed. The keying mayaccommodate an alignment of the first portion 200 and the second portion500 when the first portion 200 and the second portion 500 are joined toform subassembly 700. For example, the keying may allow only one way forfirst portion 200 to be joined with the second portion 500.

Circle 710 illustrates the joining of first portion 200 and the secondportion 500 in more detail. Referring to circle 710, ridges 420 and 520may interlock. Interlocking ridges 420 and 520 may accommodate analignment of the first portion 200 with the second portion 500. Inaddition, interlocking ridges 420 and 520 may cause one or more windows740 to be formed. The windows 740 may expose terminals 342 and terminals528. The windows 740 may be used to accommodate a joining terminals 342and terminals 528 together.

Joining terminals 342 and terminals 528 together may electrically and/ormechanically connect the first portion 200 with the second portion 500.For example, in an embodiment, a welding probe enters window 740 toelectrically and mechanically join terminals 342 and to terminals 528using a welding technique. It should be noted that other techniques maybe used to electrically and/or mechanically join terminals 342 andterminals 528 together. For example, in an embodiment, a soldering probeenters window 740 to electrically and mechanically join terminals 342 toterminals 528 using a soldering technique.

FIG. 8 illustrates an example embodiment of a third portion 800 of thespeed sensor 100 joined to subassembly 700. Referring to FIG. 7, thethird portion may be a flange that may be associated with the speedsensor 100. The flange may be used to mount the speed sensor 100 duringan operation of the speed sensor 100. The flange may include a hole 812that may be used to accommodate mounting the speed sensor 100.

The third portion 800 may be joined to subassembly 700 by over-moldingthe third point 800 over the subassembly 700. The over-molding may occurat ribs 422 and 522. The over-molded third portion 800 may cover thesubassembly 700 at a point in the subassembly 700 where the firstportion 200 and second portion 500 are joined. Moreover, over-moldingthe third portion 800 at this point of the subassembly 700 mayenvironmentally seal this point from contaminants that may otherwiseenter this point.

For example, in an embodiment, over-molding the third portion 800 on thesubassembly 700 causes a portion of the third portion 800 to flow intowindows 740 and form a seal to seal the joining of the first portion 200and the second portion 500. Moreover, this flow may act to drive out airthat may be contained at the point in the subassembly 700 where thefirst portion 200 and the second portion 500 are joined. Forcing the airout may prevent undesirable conditions that may occur if the air werepresent (e.g., oxidation of the terminals 342 and terminals 528). Inaddition, forcing the air out may improve a durability of the speedsensor 100 at the point where the first portion 200 and the secondportion 500 are joined.

Also illustrated in FIG. 8 is a placement is a seal 820. In anembodiment, seal 820 is an O-ring that is made of a pliable material. Asshown in FIG. 8, the seal 820 may be placed in groove 414. Seal 820 maybe used to prevent contaminants from migrating beyond groove 414 towardsthe second portion 500 during an operation of the speed sensor 100.

FIG. 9 illustrates a flow chart of example acts that may be performed toproduce a speed sensor. Referring to FIG. 9, at block 910 a housing forthe first portion is over-molded onto a sensing assembly to produce afirst portion of the speed sensor. The sensing assembly may be anassembly that senses a movement of an object and generate a signal basedon the sensed movement. The signal may be present on terminalsassociated with the sensing assembly. Over-molding the housing mayencase the sensing assembly except for the terminals. The housing mayact to protect certain portions of the sensing assembly fromcontamination and damage that may occur if the housing were not present.

At block 920, a seal, washer, and wiring harness is assembled to producea harness assembly. The wiring harness may contain a plurality of wires.The seal and washer may include holes through which wires contained inthe wiring harness may pass. The holes may be used to accommodate analignment of the wires.

At block 930, the harness assembly and a housing for the second portionare assembled to produce a second portion of the speed sensor. Thehousing may secure the wiring harness assembly and enable the wiringharness to be handled with ease. Moreover, the housing may protectportions of the wiring assembly from various environmental conditions.

At block 940, the first portion and the second portion are joined. Forexample, the first portion and the second portion may be keyed. Thekeying may accommodate an alignment of the first and second portionswhen joining the first and second portions. Moreover, the first andsecond portions may include terminals that may be used to make anelectrical connection between the first and second portions. Theterminals on the first portion may be joined with terminals on thesecond portion to make the electrical connection. The terminals may bejoined by welding, soldering, and/or otherwise joining the terminalstogether.

At block 950, a third portion of the speed sensor is over-molded ontothe joined first portion and second portion. The third portion may beover-molded at a point where the first and second portion are joined.Over-molding the third portion at the point may provide a seal that mayseal the point from outside contaminants. Moreover, over-molding thethird portion at the point may strengthen the speed sensor at the point.

The foregoing description of embodiments is intended to provideillustration and description, but is not intended to be exhaustive or tolimit the invention to the precise form disclosed. Modifications andvariations are possible in light of the above teachings or may beacquired from practice of the invention.

No element, act, or instruction used herein should be construed ascritical or essential to the invention unless explicitly described assuch. Also, as used herein, the article “a” is intended to include oneor more items. Where only one item is intended, the term “one” orsimilar language is used. Further, the phrase “based on” is intended tomean “based, at least in part, on” unless explicitly stated otherwise.

It is intended that the invention not be limited to the particularembodiments disclosed above, but that the invention will include any andall particular embodiments and equivalents falling within the scope ofthe following appended claims.

What is claimed is:
 1. A speed sensor comprising: a sensing assemblyincluding: a bobbin having a wire coil and a magnet for generating amagnetic field and a plurality of conductive pins in electricalconnection with the wire coil; and a lead frame affixed to the bobbin,the lead frame providing an electrical connection between the conductivepins and a plurality of first conductive terminals; a first housingover-molded to the sensing assembly, the first housing having an upperflange proximate to an open top end, wherein the first conductiveterminals protrude from the open top end; a second housing having alower flange proximate to an open lower end, the lower flange joined tothe upper flange of the first housing to form a plurality of weldwindows, wherein the second housing contains a plurality of secondconductive terminals proximate to both the open lower end and the firstconductive terminals such that the weld windows provide an opening toallow the first conductive terminals to be welded to the secondconductive terminals; and a flange overmold having a first openingoperable to join the flange overmold to both the upper flange and thelower flange to seal the first housing to the second housing and fillthe weld windows.
 2. The speed sensor of claim 1 wherein the flangeovermold includes a second opening offset from the first opening, thesecond opening operable to mount the flange overmold.
 3. The speedsensor of claim 1 wherein the second housing includes a plurality ofridges proximate to the open lower end, the ridges aligning the firsthousing and the second housing.
 4. The speed sensor of claim 1 whereinthe bobbin includes a plurality of stake pins extending perpendicular tothe conductive pins, the stake pins staking the conductive pins withinthe bobbin.
 5. The speed sensor of claim 1 wherein the magnet isdisposed within an annular ring formed by the wire coil.
 6. The speedsensor of claim 5 wherein the magnet protrudes substantially from a topopening of the annular ring and slightly from a bottom opening of theannular ring.
 7. The speed sensor of claim 6 wherein the first housingis thicker at a location proximate to the bottom opening of the annularring.
 8. The speed sensor of claim 1 wherein the flange overmold isfurther operable to seal the weld windows such that the flange overmoldflows into the weld windows driving out air.
 9. The speed sensor ofclaim 1 wherein: the first housing includes a plurality of first ribsproximate to the open top end; the second housing includes a pluralityof second ribs proximate to the open lower end; and the first opening ofthe flange overmold is operable to couple with the first ribs and thesecond ribs.
 10. A speed sensor comprising: a sensing assembly extendingsubstantially along a longitudinal axis for generating a signalassociated with a movement of an object external to the speed sensor,the sensing assembly having a plurality of conductive terminalsproximate to an upper end for transmitting the signal; a first housingextending along the longitudinal axis and over-molded to the sensingassembly, the first housing having an upper flange proximate to a topend, wherein the first conductive terminals protrude from the top end; asecond housing extending along the longitudinal axis and having a lowerflange proximate to a lower end, the lower flange joined to the upperflange of the first housing to form a plurality of weld windows, whereinthe second housing contains a plurality of second conductive terminalproximate to the lower end and the first conductive terminals such thatthe weld windows provide an opening to allow the first conductiveterminals to be welded to the second conductive terminals; a flangeovermold extending along a transverse axis and having: a first openingoperable to join the overmold to both the upper flange and the lowerflange to seal the first housing to the second housing and seal the weldwindows; and a second opening, offset from the first opening along thetransverse axis, for mounting the flange overmold.